http://www.amazon.com/Book-Stones-They-What-Teach/dp/1556436688/ref=sr_1_fkmr0_1?ie=UTF8&qid=1293622038&sr=1-1-fkmr0 The Book of Stones: Who They Are and What They Teach  by Robert Simmons and Naisha Ahsian. Great book if you already do or are considering working with stones.